In the prior art, CNC-controlled machine tools are well known that comprise at least 5 axes which make it possible to move or control a tool in 5 degrees of freedom through space in relation to a workpiece to be machined for removing material from the workpiece. CNC (“computerized numerical control”) means that the machine tool is numerically controlled, for example, by using an NC program or CNC program.
The 5 degrees of freedom comprise the at least three spatial direction degrees of freedom (conventionally, mostly three orthogonally drivable spatial direction degrees of freedom, optionally referred to as an X axis, Y axis and Z axis) which may be driven by at least three linear axes, and at least two angular or rotational degrees of freedom which enable any tool orientation in relation to the workpiece. The angular or rotational degrees of freedom may be driven by two, three or more rotational axes of the machine tool (optionally referred to as A axis, B axis and C axis). Today's CNC machine tools comprising at least 5 axes in particular make it possible to simultaneously drive the 5 degrees of freedom whereby particularly complex and efficient tool paths in relation to a clamped workpiece are enabled. Furthermore, the prior art discloses machine tools having 6 axes on which 3 linear axes and 3 rotational axes may be simultaneously driven. Machine tools comprising more than 6 axes are also possible.
The machine tools disclosed by the prior art are suited to be equipped with a tool, such as, for example, a milling or drilling tool, that removes material from the workpiece by machining. Here, the tool is controlled by a controller by using an NC program or CNC program. Thus, a precise program-controlled machining of a workpiece clamped in the machine tool by using control data becomes possible.
For rotatively driving the tool, in particular for generating a cutting movement when the workpiece is machined by the tool, machine tools known from the prior art comprise a work spindle or main spindle including a work or main spindle drive that comprises a tool holding means for holding a tool. The tool holder on the work spindle is suitable for holding tools, in particular tool interfaces, such as, for example, tool tapers. Known tool tapers are e.g. Morse tapers, steep angle tapers or also hollow shank tapers. The workpiece to be machined is clamped on a clamping means of the machine tool, in particular on a clamping means on a turntable or rotary table of the machine tool that may be rotatively driven via a rotational axis for rotatively aligning the workpiece. The turntable or rotary table may for example be further configured to be pivotably driven by means of a pivoting axis (pivoting rotary table)
Furthermore, the above-described machine tools, such as, for example, universal milling machines or other machine tools comprising a tool changer are optionally adapted to perform an automatic program-controlled tool change on the work spindle by replacing the tool clamped on the work spindle of the machine tool or the tool held on the tool holding means of the work spindle with another tool. To this end, the machine tools comprise a tool changer that is adapted to automatically replace the tool clamped on the work spindle. Moreover, the machine tool may comprise a tool magazine for storing a plurality of tools, the tool changer replacing the tool clamped on the work spindle with a tool previously stored in the tool magazine during a tool change.
According to the operating mode of a tool changer disclosed by the prior art, the tool change is performed from the tool holding means of the work spindle into the magazine or vice versa, for example, in that a gripper or gripper device, in particular a simple or double gripper device of the tool changer, grips or holds the tools or tool tapers in which the tools are held. Such tool tapers (for reception in tool holders, for example, Morse tapers, steep angle tapers, hollow shank tapers) form a standardized interface between the tool holding means of the work spindle and the tool and allow a fast change of tools with a small tool change-over time. Furthermore, the prior art discloses so-called pick-up tool changing devices or pick-up tool changers which are suitable for directly inserting or replacing a tool from the tool holding means of the work spindle into the tool magazine or vice versa.
When machining workpieces on a machine tool in accordance with the methods known from the prior art, in particular on a milling/drilling machine tool, a drilling/milling machine tool, universal milling machines or a universal machining center, a workpiece to be machined is clamped on a clamping means of the machine tool, for example, on the turntable or rotary table of the machine tool that can be rotatively driven by means of a rotational axis and/or pivotably driven by means of a pivoting axis (e.g. a pivoting rotary table) and may also optionally be moved by means of one or more linear axes, or on an NC indexing head, and furthermore a tool provided for the machining is clamped on the work spindle of the machine tool. If it is required to use different tools for the machining of a workpiece, an automatic tool change may be performed on the work spindle.
It is an object of the present invention to provide a method for machining a workpiece on a machine tool comprising at least 5 axes and including a work spindle having a tool holding means and an adequate machine tool for machining a workpiece that enables more efficient and time-saving machining of workpieces on a machine tool including a work spindle having a tool holding means in contrast to the methods disclosed by the prior art.
It is another object of the present invention to provide a more efficient and time-saving method for machining a workpiece on a machine tool including a work spindle having a tool holding means and an adequate machine tool for a small series or series production of workpieces, in particular, for example, for a small series or series production of straight-toothed, helical toothed, spiral toothed or circular arc toothed gears, such as, for example ring gears, pinions or bevel gears.